This 1997 Chevy Suburban has a 5.7-liter engine, 6-inch suspension lift, and 35-inch tires. The truck is regularly used off-highway and to tow trailers. It also has a propensity for killing its 4L60E four-speed automatic transmission.
The 4L60E transmission has been used in a slew of 1/2-ton GM trucks and SUVs, and it has even appeared in some GM 3/4-ton trucks. It's a decent transmission that has proven itself a workhorse. However, if you use your truck hard, it can be a weak point that can fail-in some cases, repeatedly.
The owner of this rig could've kept paying to have the 4L60E rebuilt, but instead chose to replace it with the much beefier 4L80E four-speed automatic transmission. The 4L80E has been used in a number of 1/2-, 3/4-, and 1-ton GM trucks over the years. Upgrading from the 4L60E to the 4L80E is akin to going from a Dana
44 axle to a Dana 60--you'll add some weight, but also add durability. According to GM Powertrain information, the 4L60E has a maximum engine torque rating of 360 lb-ft and a maximum gearbox torque rating of 610 lb-ft.
The 4L80E has a maximum engine torque rating of 440 lb-ft and a maximum gearbox torque rating of 885 lb-ft. What this boils down to is that the 4L80E offers an 80 lb-ft and 275 lb-ft improvement over the 4L60E in both areas, respectively. Is there a downside? Well, the 4L80E is slightly heavier and offers a less crawly First gear ratio (2.48:1) than the 4L60E (3.06:1).
Matt Dinelli and his team at Attitude Performance in Arlington Heights, Illinois, have completed a number of 4L80E swaps on fullsize GM trucks. We recently had the chance to witness one of these swaps on the aforementioned vehicle. Here are the highlights.